Sedimentary Facies Of Wutonggou Formation In Beisantai Area In Junggar Basin

In this paper, with sequence stratigraphy theory and methods, we make a comprehensive analysis of the drilling, core, logging and three-dimensional seismic data, thinking that Wutonggou Formation in Beisantai area of Permian as a third group, the top and bottom interface with the special province of sequence boundaries, named PSB1 and TSB2. In Wutonggou sequence(SQP3wt), we identify six sequence boundaries and a maximum flooding surface, dividing it into two systems tracts, and seven parasequence sets (PS1, PS2, PS3, PS4, PS5, PS6, PS7). PS1-PS4 is transgressive system, PS5-PS7 is regression system. Based on these, we established the parasequence level of correlation framework in the well sections on Wutonggou sequence(SQP3wt) in Beisantai area of Permian.We make source analysis, sedimentary facies type and distribution of sedimentary facies within sequence stratigraphy framework, thinking that there are three source system from the beautiful mountain of carats, the southern Bogda Mountain and Beisantai raised. In the period of the SQP3wt deposition, the beautiful mountain of carats and Bogda Mountain are the persistent sources. In transgressive system period, Beisantai preiection is the source, it uplifted and sufferred denudation; In regression system period, because of denudation and tectonic subsidence, Beisantai preiection was submerged in the water, no longer as the source in study area.Analysis of rock types, sedimentary structures, debris particle characteristics and logging characteristics of facies, thinking that Wutonggou sequence (SQP3wt) develop fan delta, delta and lake of three facies. Fan delta develop fan delta front subfacies, especially develop these microfacies: underwater distributary channel, distributary channel between themicro-phase, delta also develop delta front. The main types of micro-phase is far sand bar and mouth bar, and can also be identified underwater distributary channel, distributary channel between the other micro-facies. Lake facies develop shallow lake subfacies and semi-deep–lake - deep lake, and can also see the beach bar of small scale. During transgressive systems tract of SQP3wt deposition, Beisantai area mainly develops fan-delta sedimentary systems, that are Carat beautiful mountain fan delta sedimentary system in northern part , Bogurda mountain fan delta sedimentary system in southern part and fan delta sedimentary system around Beisantai preiection. During the period of regressive systems tract, the study area develops two delta systems, which are Carat beautiful mountain delta in the north and Bogurda mountain delta in the south.